The “closed delta” and “open delta” transformer configurations are methods of connecting three-phase transformers to create a three-phase system. Let’s delve into each configuration:
- Closed Delta Transformer (also known as “D” or “Dy” Connection): In a closed delta configuration, three single-phase transformers are interconnected to form a closed loop. This configuration provides both three-phase and single-phase power connections.
The primary and secondary windings of each transformer are connected in a way that creates a closed triangular loop. The closed delta can provide three-phase power and also support single-phase loads. However, it has a lower capacity compared to other configurations due to the inherent limitations of the winding connections.
Closed delta transformers are used in situations where the load requirements are not too high and where the load is predominantly three-phase but may also include some single-phase loads.
- Open Delta Transformer (also known as “V” or “Vy” Connection): The open delta configuration involves using only two transformers out of the three, resulting in a lower capacity compared to the closed delta configuration. This configuration is primarily used when one of the transformers fails, and the system needs to be temporarily maintained using the remaining two transformers.
The primary and secondary windings of two transformers are connected, and the third transformer is disconnected. This setup provides three-phase power but cannot support single-phase loads directly. The capacity of the open delta is typically around 86.6% of the closed delta capacity.
Open delta configurations are used in situations where redundancy and temporary maintenance are critical. However, it’s important to note that if one transformer fails, the capacity of the system will be reduced, and it should be restored to full capacity as soon as possible.
It’s worth mentioning that both the closed delta and open delta configurations have their own advantages and disadvantages. The choice between them depends on factors such as load requirements, redundancy needs, and system reliability considerations. Additionally, these configurations are just two of several possible ways to connect three-phase transformers, each with its own specific applications and benefits.